Summary

Adding some text in Code block sometimes turns to markdown block.

Environment

Firefox 63.0

Steps to Reproduce

1. Add a Code Block Macro to a page
2. Insert something in the block
3. Delete the entered characters with backspace
4. Type something that could be interpreted as Markdown eg "# foo" or "* bar"

Expected Results

Text in Code block macro should not be rendered as like markdown

Actual Results

The entered text either disappears or gets rendered as like markdown

Workaround

User another browser like Google Chrome